Hybrid Electric Vehicle example essay topic

Through the early period of the automotive industry until about 1920, electric automobiles were competitive with petroleum-fueled cars particularly as luxury cars for urban use and as trucks for deliveries at closely related points, for which the relatively low speed and limited range, until battery recharge, were not detrimental. Electrics, many of which were steered with a tiller rather than a wheel, were especially popular for their quietness and low maintenance costs. Ironically, the death knell of the electric car was first tolled by the Kettering electrical self-starter, first used in 1912 Cadillac and then increasingly in other gasoline-engine cars. Mass production, led by Henry Ford, also reduced the cost of the non-electrics. Electric trucks and buses survived into the 1920's, later than passenger cars, especially in Europe. Electric automobile prototypes reappeared in the 1960's when major U.S. manufacturers, faced with ultimate exhaustion of petroleum-based fuels and with immediate rising fuel costs from the domination of Arab petroleum producers, once again began to develop electrics.

Both speed and range were increased, and newly developed fuel cells offered an alternative to batteries; but by the mid-1980's electric automobiles had not become a part of the automotive industry's output. Most industrial in-plant carrying and lifting vehicles, however, were electrically powered. Why were hybrid-electric vehicles developed? There are several reasons for this. Standing at the gas pump, watching the dollar total spin up into the stratosphere, have not many of us dreamed of owning an electric-powered car that can thumb its hood ornament at the oil companies as it whizzes us ever so quietly by their filling stations? Aside from the promise of oil independence, there is the very real need to reduce environmentally polluting vehicle emissions.

For now, electric vehicles are the only cars available to consumers that qualify as zero-emissions vehicles (ZEV) under emerging regulatory standards. Yet despite some progress in the development and production of electric vehicles, their advancement seems stuck in the stop-and-go traffic jam of battery development. Building pure electric vehicles with a just-adequate driving range still requires a heavy array of expensive batteries, which pushes up the vehicles sticker price to levels that discourage all but the most gun ho electric-car enthusiasts. In time, that situation may change.

But for now, it appears that hybrid-electric vehicles stand a much better chance of electrifying the automotive world. The current crop of hybrid-electric vehicles (HEVs), both those in production and those in the pre production prototype stage, supplement the driving power supplied by the conventional internal-combustion engine. They do this by incorporating an electric motor, a more powerful alternator, and a higher-capacity battery into the vehicles power train. HEVs can be configured as either series, parallel, or series-parallel combinations of gas and electric power. While these cars do not eliminate vehicle emissions, they do significantly reduce them.

Even organizations such as the California Air Resources Board (CARB), which is pushing car makers to ramp up production and sales of electric vehicles, have recognized that HEVs will play a key role in satisfying stricter environmental regulations. Ford Motor Co. is one automaker that believes the future for electric vehicles may lie in niche markets such as neighborhood vehicles. By developing the Think city vehicles, this maker is developing cars that are not powerful enough for highway driving but are sufficient for use in urban environments or gated communities. There are a few reasons why HEVs are now considered better candidates for high-volume production than pure electric vehicles. Above all else, hybrids offer a better ratio of price to performance. This reflects a number of differences between the two vehicle types.

Because the hybrid does not rely strictly on electric drive, HEVs get by with few batteries and a smaller electric motor, cutting down on both the cost and weight of these elements. Moreover, a hybrid power train does not require lengthy and perhaps inconvenient recharging of batteries. And, despite its limitations in the amount of electric drive power and energy storage, hybrid-concept vehicles are achieving fuel economy ratings of 80 miles per gallon. How do they do it? HEVs exploit a number of gas-saving techniques.

One is stop-start operation, a method that shuts down the gas engine when the vehicle stops, saving fuel consumed during idle periods. When the driver accelerates after stopping, the electric motor kicks in, propelling the car forward and restarting the combustion engine. The electric drive may also provide a boost to the engine as needed. That electric-motor assistance allows the use of a smaller, lighter engine, as it can be sized to accommodate average rather than peak loads. In turn, this allows an improvement in the operating efficiency of the engine.

Another tool available to HEVs is regenerative braking. It recovers the energy used to slow down or stop a vehicle, converting mechanical braking energy from the combustion engine back to electrical energy, which is then stored in the battery. Optimizing all of the electrical and electronic elements of the power train achieves additional gains in fuel efficiency. These components include the electric motor, alternator, batteries, and power-conversion and management circuitry. Beyond the electrical system, there also is the need to reduce the total weight of the entire vehicle. To this end, HEV designs are turning to special lightweight materials that replace steel auto-body components with aluminum and molded plastic parts.

With all elements of HEV design, the availability of low-cost manufacturing processes is critical to make the technology feasible. One major incentive for HEV development is that it makes maximum use of the existing automotive manufacturing infrastructure and supply chain. Another factor favoring hybrids is the increasing demand for electrical power in the car. HEVs, which boost the cars power-generating capacity for propulsion, also make more electrical power available to power-train components and the growing list of vehicle accessories.

Without a migration to hybrid designs, vehicles will either suffer degradation in fuel efficiency or else face more-restrictive electrical power budgets. Hybrid designs will not only make more electrical power available for running the car and its accessories, they also will foster the development of better energy management systems. These will implement higher-voltage systems, improvements in batteries and other energy storage devices, advanced electrical generator design / motor design, more-efficient power-conversion components, and sophisticated control schemes to optimize power management. Hybrid vehicles have been on the market for some time, although they have been limited in availability.

One of the first, Toyota Prius, was introduced in Japan in 1997. A revamped version appeared this past year in the U.S. and Europe. The Prius employs a combination series-parallel design to achieve better than 50-mpg fuel efficiency. It seems to support the contention that HEVs are truly on the rise. Supposedly, a little more than a year and a half after the Prius was introduced in Japan; it sold more units than any of the electric vehicles introduced over the past 30 years. The first hybrid-electric vehicle to hit U.S. shores, the two-s eater, five-speed manual Honda Insight uses an integrated motor assist (IMA) system.

The system combines a 1.0-liter, three-cylinder gasoline engine with a small electric motor. The electric motor is powered by a 144-V nickel metal hydride battery pack located under the rear hatch. Regenerative braking charges the batteries. When coasting or braking, the IMA captures energy normally lost though brake or engine heat. In the 73-hp engine, the cylinders are offset from the crankshaft. When the spark plugs fire, the connecting rods are straight up, reducing force on the side cylinder walls.

This cuts down on friction, squeezes more power out of the engine, and improves fuel economy. A he mi-head engine design has four valves per cylinder with a spark plug in the center and runs at a 10.5: 1 compression ratio. The valve train opens only one intake and exhaust valve at low speeds to reduce fuel consumption and, at higher speeds, opens all four. Each iridium-tipped spark plug uses direct injection to burn fuel more efficiently.

This two-s eater is able to achieve fuel efficiency greater than 60 mpg. But even more impressive HEV performance is in the works, thanks to an ongoing effort known as the Partnership for a New Generation of Vehicles (PNGV). The PNGV is an initiative sponsored by both the domestic auto industry and the U.S. government. Its goal has been to produce vehicles with up to 80-mpg fuel efficiency or roughly three times the fuel economy of a 1993 model, family-size sedan. Makers have to produce these cars at costs equivalent to conventional vehicles. Aluminum plays a big role in the Insight.

The 1.0-liter engine has an aluminum block, an aluminum head and exhaust manifold, and weighs in at a light 124 lb. The aluminum body and chassis cut overall vehicle weight and are joined together by die cast pieces for strength. The chassis uses aluminum pipes with internal ribs for strength at the front and rear. For safety's sake, these extrusions fold up in an accident like a paper fan, absorbing the impact and pushing the energy upward as the frame bends. Aluminum beams protect against side impacts.

The Insight has a 0.25 Cd, thanks to a tapered body, rounded noise, rear-wheel skirts, low height, and a flat underbody. And while it is environmentally friendly, performance figures state 110 mph and 0 to 60 in 12 sec. The program proposes that car makers achieve these goals by reducing vehicle weight up to 40%, by raising engine efficiency as much as 40% to 55%, by implementing regenerative braking and by increasing energy storage up to 90%. The PNGV timeline calls for automakers to build their concept vehicles by 2000 and have pre production prototypes ready by 2004. All three automakers Ford, General Motors Corp., and Daimler Chrysler Corp. did in fact introduce their PNGV concept cars early last year.

A peek under the hood reveals some commonalities among the designs (Fig. 3). For instance, each vehicle employs parallel-hybrid designs with diesel direct injection. Battery types, voltage levels, the amount of regeneration used, motor types, and other design factors vary from company to company, however. Meeting the goals set forth by the PNGV presents complex system-level design challenges. In terms of the PNGV cars electrical system, all elements and subsystems associated with power generation, conversion, storage, distribution, and management must be optimized.

Given the extensive nature of development on hybrid component and system design, it is only possible to offer a sampling of notable developments here. But these advances might indicate some of the ways in which HEV designs are evolving. New hybrid-electric vehicles perform as well as some conventionally powered models. A senior editor at a big-name car magazine relates what happened a few years ago when editors there road tested one of the first electric vehicles available to the public. The plan was not to baby the car.

It would undergo the same braking and acceleration tests that ordinary vehicles went through during an evaluation. The road test lasted less than a mile before the batteries were toast. The automaker came out and took back its creation in a huff, accompanied by a lot of hooting on the part of the automotive journalists involved. It looks as though automakers need no longer fear similar embarrassments. The new crop of alternative power vehicles now reaching showrooms can hold their own against more traditional designs. These hybrid electrics combine a small diesel or gas engine with generators / motors to meet goals defined by the Partnership for a New Generation of Vehicles (PNGV).

Honda beat the bunch to the market by offering the Insight, a two-s eater vehicle that gets up to 70 mpg and garnered an award from the tree-hugging Sierra Club. Toyota is following suit this summer by introducing its Prius to the U.S., currently a big seller in Japan. Ford and GM are developing hybrids for production by 2004. Daimler Chrysler is bringing up the rear and will introduce a concept hybrid later this year, but claims it will also have one in production by 2004 as well. Toyota Prius runs on either electricity or gasoline, or a combination of the two. The key to the hybrid system is a power split device which sends engine power directly to the wheels or to an electric generator that controls the electric motor and battery charge.

This device uses a planetary gear to vary the amount of power supplied from the engine to either the wheels or the generator. This gear set controls engine speed independent of road speed to wring maximum fuel efficiency out of the power plant. An electronically controlled transmission adjusts the rates of revolution of the gasoline engine, electric generator, and electric motor for acceleration and deceleration. The primary power source for the Prius is a 1.5-liter gasoline engine. Specs for the Japanese model state the power plant provides 58 hp at 4,000 rpm with peak torque of 75 lb-ft at 4,000 rpm. The U.S. models are expected to have an increase in horsepower and torque.

Limiting engine revs to 4,000 rpm lets internal parts be built lighter. Also, the crankshaft has a smaller diameter, piston rings have lower tension, and the valve spring load is less compared to high-revving engines. The permanent-magnet electric motor generates 30 kW, or 40 hp from 940 to 2,000 rpm. A regenerative braking system turns the motor into a generator when brakes are applied or the vehicle is coasting. This captures energy normally lost as heat or kinetic energy and transforms it into electricity to recharge the batteries. A computer sends a signal to the regenerative system to slow the vehicle when the driver presses the brake.

Pushing the pedal harder makes hydraulic brakes kick in. The Prius has front discs with rear drums, and standard ABS. The Prius carries a hydrocarbon adsorption catalyst and a vapor-reducing gas tank to meet Su lev specs. The catalyst uses what is said to be the thinnest-walled ceramic substrate with a high cell density. This increases catalytic surface area, raising efficiency. A hydrocarbon adsorbing unit catches and stores HCs on its surface until the catalyst warms to operating temperature.

Many different car models are now being offered with hybrid power plants, and many more other will appear in the next few years. Currently hybrid-electric vehicles are about $2,000 to $6,000 more expensive than their usual counterparts. A person who will purchase a hybrid-electric vehicle will not necessarily make all that money back by saving on gas; however, it will be possible for that lucky person to drive around with a very nice, holier-than-thou feeling. Moreover, this will make an owner confident that he or she is actually helping to save our planet and reducing the dependence on depleting oil resources. I believe that hybrid-electric vehicle is a great invention, which will help to develop more sophisticated alternatively powered models in the future.